package com.android.kotlin

import org.junit.Test

import org.junit.Assert.*

/**
 * Example local unit test, which will execute on the development machine (host).
 *
 * See [testing documentation](http://d.android.com/tools/testing).
 */
class ExampleUnitTest {
    @Test
    fun addition_isCorrect() {
        var a: String? = null
        var b = a?.length ?: 100  //左边为null，返回右边的100
//        println(a?.length ?: 100)  //输出： 100
        println(a?.length)
    }
}
